Atlanta, Georgia (CNN) -- Atlanta's public school system was told Tuesday it has until September 30 to make progress on a series of recommendations or risk its high schools' losing their accreditation, a fate that would affect the college hopes of many of the system's graduates.

The probation placed on the system's high schools stems from complaints that conflicts between members had severely hampered the school board's ability to govern effectively, according to a statement from AdvancEd, the world's largest school accrediting agency and the parent company of the Southern Association of Colleges and Schools.

"This is designed to improve the school system," Mark Elgart, president and CEO of AdvancED, said at a news conference Tuesday. "The (school) board and the system have a choice here: They can choose to proactively take actions designed to improve it, building on these actions we have outlined, or they can fight it."

Members of Atlanta Public Schools Board of Education met in a special session Tuesday afternoon to review the report, and will vote next week to formally accept it, the Atlanta Journal-Constitution reported. Elgart will be at next week's meeting to answer board members' questions, the newspaper said.

The action is a "grave moment in our history, but one that we must resolve," board member Reuben McDaniel told CNN affiliate WXIA.

AdvancED conducted a special review looking into -- among other things -- a leadership shakeup initiated by the school board last summer. The board changed its policy to allow a simple majority vote to change the chair and vice chair positions, despite outside legal advice that such a policy change would be illegal. Ultimately, a lawsuit was filed challenging the move.

The special review also found that the board circumvented its own procurement policies in approving a contract for a communications vendor, and that the "fallout" from the friction on the board had become a distraction to staff.

According to AdvancED, the steps the school system must take to show progress include: developing a plan to effectively communicate is mission to staff and other "stakeholders;" hiring a trained mediator to work with board members to resolve issues; ensuring that board policies -- "especially those related to ethics and chain of command" -- are understood and followed; and coming up with a plan for selecting a superintendent that "demonstrates integrity throughout the process."

Atlanta Public Schools, which has 47,000 students, is the second large school system to have schools placed on probation, and the second in the metro area, according to Jennifer Oliver, vice president for communications for the Southern Association of Colleges and Schools. Schools in Clayton County, south of Atlanta, lost their accreditation in 2008 and are approaching the end of a two-year probation.

In an e-mail response to a question from CNN, Oliver cautioned that Atlanta's public high schools "are still accredited, and it's too early to speculate on about whether (the schools) will lose their accreditation." However, she said, a loss of accreditation could mean that "graduating seniors may be limited in scholarships and college admissions if a program requires students to come from an accredited institution and/or uses accreditation of the high school as part of the criteria for evaluating students."

The school system, which had won national awards for closing academic gaps in recent years, was rocked last year by allegations of cheating on standardized tests given to elementary and middle school students. An independent commission found that employees at 12 schools had violated testing protocols, the Journal-Constitution reported in June 2010.

Because AdvancED only accredits Atlanta's public high schools, it isn't involved in the test-cheating investigation. "However," Oliver said, "how the board addresses the results of the investigation as leaders of the school system will be of interest to (AdvancED) in regards to the Accreditation Standard of Governance and Leadership, which they are currently not meeting."